The present invention relates to a method for vulcanizing a prevulcanized, particularly flat profiled tread, also in annular form by means of an unvulcanized bonding rubber intermediate layer, particularly in the form of a bonding rubber plate onto a vehicle tyre accompanied by pressure application in a chamber heated with steam, a steam-air mixture, air or water.
In a known method of this type the built tyre is at least outwardly sealingly enclosed by a casing. The chamber between the built tyre and the casing is either subjected to the action of a vacuum from the inside and/or overpressure from the outside, so that the casing rests tightly against the applied tread and whereby either under the action of the vacuum or through the action of the externally applied overpressure or through the vacuum and overpressure simultaneously any air occlusions are removed or forced from the tyre structure or from the chamber between the casing and the built tyre. Simultaneously, the casing applied to the tyre under a vacuum and/or overpressure brings about the cohesion of the built tyre, so that for example the edges of the tread cannot lift from the carcase during the reduction of the adhesive power of the bonding rubber resulting from the temperature. Flexible casings of this type are relatively expensive and have only a limited life, whilst their flexibility is also time-dependent.
Attempts have also already been made, without using a flexible casing of the type indicated hereinbefore to securely grip the tread all round in order to avoid any detachment of the tread during the first phase of the heating process. However, it has been found that the fixed clamping members used for clamping the built tyre cause undesired buckling or deformation of the tyre and also an undesired displacement of the tread relative to the carcase through a non-uniform distribution of the pressure exerted. It has hitherto not proved possible to avoid such displacements of the tread and deformations of the tyre.